Fertility partially drives the relative success of two introduced bovines (Bubalus bubalis and Bos javanicus) in the Australian tropics

2011 ◽  
Vol 38 (5) ◽  
pp. 386 ◽  
Author(s):  
Clive R. McMahon ◽  
Barry W. Brook ◽  
David M. J. S. Bowman ◽  
Grant J. Williamson ◽  
Corey J. A. Bradshaw
Keyword(s):  
Population Growth ◽  
Bubalus Bubalis ◽  
Ex Situ ◽  
High Survival ◽  
Population Densities ◽  
Large Herbivore ◽  
Large Herbivores ◽  
Ecological Damage ◽  
Bos Javanicus ◽  
Demographic Performance

Context Some large herbivores introduced to Australia have achieved population densities so high as to cause considerable ecological damage. Intriguingly, others have been relatively less successful and have correspondingly perturbed their new environments less. An excellent example is two similar-sized bovine species that established feral populations in the Northern Territory of Australia in the mid-19th century. Asian swamp buffalo (Bubalus bubalis) rapidly colonised the tropical savannas, causing ecological degradation, especially on freshwater swamps. In contrast, banteng (Bos javanicus) are restricted to their point of introduction and have caused relatively negligible ecological damage. Understanding the reasons of this differential success is of theoretical and applied interest and contributes to managing large herbivore populations for ex situ conservation and feral-animal control. Aims To compare the population structure of buffalo and banteng on the basis of shot samples, so as to construct life tables for four contemporary (low-density) buffalo populations, and collated data from previous work from three historical (high-density) buffalo populations and one banteng population (the only extant ex situ population in existence). Further, to provide a validation of age estimation with and without informed priors in a Bayesian model comparing horn length and ages estimated from tooth cementum annuli. Finally, to interpret our results in the context of relative invasion potential of the two bovid species. Key Results For both species, survival of juveniles was the most important demographic component influencing deterministic population growth. However, buffalo have the demographic capacity to recover swiftly after control because of high survival and fertility rates across a range of population densities. Fertility of buffalo was historically greater than that of banteng, and buffalo fertility increased as their populations were reduced. Conclusions These findings highlight how subtle differences in demographic rates and feeding ecology can influence the success (high population growth and range expansion) of large herbivores, knowledge which is increasingly important for managing invasive species effectively. Implications We show that that individual life-history traits and demographic performance, especially fertility, play an important role in determining the spread of invasive bovids in a novel environment.

scholarly journals Demographic performance of a large herbivore: effects of winter nutrition and weather

Ecosphere ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Nathan J. Jackson ◽  
Kelley M. Stewart ◽  
Michael J. Wisdom ◽  
Darren A. Clark ◽  
Mary M. Rowland
Keyword(s):  
Large Herbivore ◽  
Demographic Performance

Plant Resistance in Some Modern Soybean Varieties May Favor Population Growth and Modify the Stylet Penetration of Bemisia tabaci (Hemiptera: Aleyrodidae)

2021 ◽  
Author(s):  
Mauricélia F Almeida ◽  
Clébson S Tavares ◽  
Euires O Araújo ◽  
Marcelo C Picanço ◽  
Eugênio E Oliveira ◽  
...  
Keyword(s):  
Population Growth ◽  
Bemisia Tabaci ◽  
Intrinsic Rate ◽  
Reproductive Rate ◽  
Genetically Engineered ◽  
Population Increase ◽  
Net Reproductive Rate ◽  
Bt Toxin ◽  
Demographic Performance

Abstract Complaints of severe damage by whiteflies in soybean fields containing genetically engineered (GE) varieties led us to investigate the role of transgenic soybean varieties expressing resistance to some insects (Cry1Ac Bt toxin) and to herbicide (glyphosate) on the population growth and feeding behavior of Bemisia tabaci (Gennadius) MEAM1 (Hemiptera: Aleyrodidae). In the laboratory, the whiteflies reared on the GE Bt soybeans had a net reproductive rate (R0) 100% higher and intrinsic rate of population increase (rm) 15% higher than those reared on non-GE soybeans. The increased demographic performance was associated with a higher lifetime fecundity. In electrical penetration graphs, the whiteflies reared on the GE soybeans had fewer probes and spent 50% less time before reaching the phloem phase from the beginning of the first successful probe, indicating a higher risk of transmission of whitefly-borne viruses. Data from Neotropical fields showed a higher population density of B. tabaci on two soybean varieties expressing glyphosate resistance and Cry1Ac Bt toxin. These results indicate that some GE soybean varieties expressing insect and herbicide resistances can be more susceptible to whiteflies than non-GE ones or those only expressing herbicide resistance. Most likely, these differences are related to varietal features that increase host-plant susceptibility to whiteflies. Appropriate pest management may be needed to deal with whiteflies in soybean fields, especially in warm regions, and breeders may want to consider the issue when developing new soybean varieties.

scholarly journals Continuous presence of proto-cereals in Anatolia since 2.3 Ma, and their possible co-evolution with large herbivores and hominins

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Valérie Andrieu-Ponel ◽  
Pierre Rochette ◽  
François Demory ◽  
Hülya Alçiçek ◽  
Nicolas Boulbes ◽  
...  
Keyword(s):  
Large Herbivore ◽  
Large Lakes ◽  
Coprophilous Fungi ◽  
Large Herbivores ◽  
Genetic Modifications ◽  
Bioclimatic Zone ◽  
Central Resource ◽  
Sedimentary Core ◽  
Continuous Presence ◽  
Lake Acıgöl

AbstractCereals are a central resource for the human diet and are traditionally assumed to have evolved from wild grasses at the onset of the Neolithic under the pressure of agriculture. Here we demonstrate that cereals may have a significantly longer and more diverse lineage, based on the study of a 0–2.3 Ma, 601 m long sedimentary core from Lake Acıgöl (South-West Anatolia). Pollen characteristic of cereals is abundant throughout the sedimentary sequence. The presence of large lakes within this arid bioclimatic zone led to the concentration of large herbivore herds, as indicated by the continuous occurrence of coprophilous fungi spores in the record. Our hypothesis is that the effects of overgrazing on soils and herbaceous stratum, during this long period, led to genetic modifications of the Poaceae taxa and to the appearance of proto-cereals. The simultaneous presence of hominins is attested as early as about 1.4 Ma in the lake vicinity, and 1.8 Ma in Georgia and Levant. These ancient hominins probably benefited from the availability of these proto-cereals, rich in nutrients, as well as various other edible plants, opening the way, in this region of the Middle East, to a process of domestication, which reached its full development during the Neolithic.

Population structure, density and biomass of large herbivores in the tropical forests of Nagarahole, India

1992 ◽  
Vol 8 (01) ◽  
pp. 21-35 ◽  
Author(s):  
K. Ullas Karanth ◽  
Melvin E. Sunquist
Keyword(s):  
Population Structure ◽  
Tropical Forests ◽  
Primate Species ◽  
Line Transect ◽  
Large Herbivore ◽  
Large Herbivores ◽  
Transect Sampling ◽  
Structure Density ◽  
Density And Biomass ◽  
Turn Over

ABSTRACTWe studied the population structure, density and biomass of seven ungulate and two primate species in the tropical forests of Nagarahole, southern India, using line transect sampling and roadside/platform counts, during 1986–87. The estimated ecological densities of large herbivore species in the study area are: 4.2 muntjac km−2, 50.6 chital km−2, 5.5 sambar km−2, 0.8 four-horned antelope km−2, 9.6 gaur km−2, 4.2 wild pig km−2, 3.3 elephant km−2, 23.8 hanuman langur km−2and 0.6 bonnet macaque km−2. Most ungulates have female-biased adult sex ratios. Among common ungulate species, yearlings and young of the year comprise about a third of the population, suggesting relatively high turn-over rates. Three species (muntjac, sambar and four-horned antelope) are solitary, while others form groups. The study area supports a wild herbivore biomass density of 14,744 kg km−2. Among the three habitat types within the study area, biomass is lower in dry deciduous forests when compared with moist deciduous or teak plantation dominant forests. Using our results, we have examined the factors that may contribute towards maintenance of high ungulate biomass in tropical forests.

Large herbivores suppress liana infestation in an African savanna

2021 ◽  
Vol 118 (41) ◽  
pp. e2101676118
Author(s):  
Tyler C. Coverdale ◽  
Ryan D. O’Connell ◽  
Matthew C. Hutchinson ◽  
Amanda Savagian ◽  
Tyler R. Kartzinel ◽  
...  
Keyword(s):  
Stable State ◽  
Life Forms ◽  
Tree Canopy ◽  
Alternative Stable State ◽  
African Savanna ◽  
Large Herbivore ◽  
Large Herbivores ◽  
Woody Vines ◽  
Plant Life Forms ◽  
Canopy Area

African savannas are the last stronghold of diverse large-mammal communities, and a major focus of savanna ecology is to understand how these animals affect the relative abundance of trees and grasses. However, savannas support diverse plant life-forms, and human-induced changes in large-herbivore assemblages—declining wildlife populations and their displacement by livestock—may cause unexpected shifts in plant community composition. We investigated how herbivory affects the prevalence of lianas (woody vines) and their impact on trees in an East African savanna. Although scarce (<2% of tree canopy area) and defended by toxic latex, the dominant liana, Cynanchum viminale (Apocynaceae), was eaten by 15 wild large-herbivore species and was consumed in bulk by native browsers during experimental cafeteria trials. In contrast, domesticated ungulates rarely ate lianas. When we experimentally excluded all large herbivores for periods of 8 to 17 y (simulating extirpation), liana abundance increased dramatically, with up to 75% of trees infested. Piecewise exclusion of different-sized herbivores revealed functional complementarity among size classes in suppressing lianas. Liana infestation reduced tree growth and reproduction, but herbivores quickly cleared lianas from trees after the removal of 18-y-old exclosure fences (simulating rewilding). A simple model of liana contagion showed that, without herbivores, the long-term equilibrium could be either endemic (liana–tree coexistence) or an all-liana alternative stable state. We conclude that ongoing declines of wild large-herbivore populations will disrupt the structure and functioning of many African savannas in ways that have received little attention and that may not be mitigated by replacing wildlife with livestock.

scholarly journals Sex Allocation, Diet, and Small Population Management of African Rhinoceros

2021 ◽  
Author(s):  
◽  
Elizabeth Victoria Berkeley
Keyword(s):  
Sex Ratio ◽  
Population Growth ◽  
Survival Probability ◽  
Sex Allocation ◽  
Sex Ratios ◽  
Small Population ◽  
Ex Situ ◽  
Sex Bias ◽  
Theoretic Approach ◽  
Wet Season

<p>The application of sex allocation theory can provide useful insight into endangered rhinoceros biology to improve in situ and ex situ conservation efforts by understanding the factors that cause a female to produce one sex of calf. By decreasing the birth sex ratio (number of males born per number of females born) in a population it may be possible to increase population growth rates. The first aim was to determine if an environmentally cued sex allocation response occurred in black rhinos. By examining rainfall and calf sex records in a wild black rhino population, I identified that birth sex ratios increase in rainy seasons and rainy years. Mothers were more likely to be observed with male calves if they conceived during the wet season (57.3% male) than during the dry season (42.9% male). Mothers were more likely to raise male calves if they conceived during wet years (60.2% male) than during dry years (46.1% male). Next, I examined whether pulsatile or random variation in sex ratios of different magnitudes, as might occur under changes in climate patterns, would be detrimental to rhinoceros population growth. Results demonstrated that while random increases in the magnitude of birth sex ratio variation, in either direction, increased population survival probability up to 0.907, sequential pulsed years of birth sex ratio bias had the opposite effect on population performance down to a survival probability of 0.619. Furthermore, for both scenarios, populations of less than 50 animals are particularly vulnerable to extinction. Since the sex biases observed in the captive rhinoceros population were attributed to several factors, I used an information theoretic approach to evaluate the relative importance of different hypotheses for birth sex bias for predicting calf sex. The results demonstrated that none of the models tested were greatly predictive of calf sex. Suspecting that the mechanisms that were cueing calf sex occur close to the time of conception and were nutritionally cued, in the final experiment, I measured changes in blood glucose in white rhinos after they ate different meals. At 90 minutes, serum glucose levels in rhinos eating the 10 % lucerne hay diet were significantly lower than the 5% glucose and 10% glucose diets but not the 10% pellet nor 10% grass hay diets. This is the first time such an experiment has been published in a wildlife species and not only demonstrates the feasibility of training rhinos for successive blood draws but also that captive diets are low glycemic for white rhinos. Overall, my research confirmed that an environmentally cued sex allocation response does occur in African rhinos, and changes in the duration and magnitude of sex ratio patterns can decrease population growth and increase potential for extinction. Additionally, none of the previous hypotheses for the suspected male-sex bias in captive born rhinos were influential on calf sex, which shifts the focus of sex allocation research in rhinos to more acute signals around the time of conception, such as changes in diet and body condition.</p>

scholarly journals The shape of density dependence and the relationship between population growth, intraspecific competition and equilibrium population density

2018 ◽  
Author(s):  
Emanuel A. Fronhofer ◽  
Lynn Govaert ◽  
Mary I. O’Connor ◽  
Sebastian J. Schreiber ◽  
Florian Altermatt
Keyword(s):  
Population Growth ◽  
Growth Models ◽  
Population Level ◽  
Logistic Growth ◽  
Population Densities ◽  
Density Regulation ◽  
Logistic Growth Model ◽  
Regulation Functions ◽  
Consumer Resource ◽  
Population Growth Models

AbstractThe logistic growth model is one of the most frequently used formalizations of density dependence affecting population growth, persistence and evolution. Ecological and evolutionary theory and applications to understand population change over time often include this model. However, the assumptions and limitations of this popular model are often not well appreciated.Here, we briefly review past use of the logistic growth model and highlight limitations by deriving population growth models from underlying consumer-resource dynamics. We show that the logistic equation likely is not applicable to many biological systems. Rather, density-regulation functions are usually non-linear and may exhibit convex or both concave and convex curvatures depending on the biology of resources and consumers. In simple cases, the dynamics can be fully described by the continuous-time Beverton-Holt model. More complex consumer dynamics show similarities to a Maynard Smith-Slatkin model.Importantly, we show how population-level parameters, such as intrinsic rates of increase and equilibrium population densities are not independent, as often assumed. Rather, they are functions of the same underlying parameters. The commonly assumed positive relationship between equilibrium population density and competitive ability is typically invalid. As a solution, we propose simple and general relationships between intrinsic rates of increase and equilibrium population densities that capture the essence of different consumer-resource systems.Relating population level models to underlying mechanisms allows us to discuss applications to evolutionary outcomes and how these models depend on environmental conditions, like temperature via metabolic scaling. Finally, we use time-series from microbial food chains to fit population growth models and validate theoretical predictions.Our results show that density-regulation functions need to be chosen carefully as their shapes will depend on the study system’s biology. Importantly, we provide a mechanistic understanding of relationships between model parameters, which has implications for theory and for formulating biologically sound and empirically testable predictions.

Rewilding

Ecology ◽  
2019 ◽  
Author(s):  
Meredith Root-Bernstein
Keyword(s):  
The United States ◽  
Large Species ◽  
Large Carnivores ◽  
Apex Predators ◽  
Ecological Processes ◽  
Large Herbivore ◽  
Large Herbivores ◽  
True Nature ◽  
The Public ◽  
Wide Range

Rewilding is an increasingly recognized approach to conservation and restoration, among academics, land managers, and the public. Although a number of different definitions have been proposed for rewilding (see Definitions of Rewilding), most approaches called “rewilding” include ideas about restoring a habitat to a less-anthropogenic state, restoring ecological processes and allowing them to take their own course without managing for a target ecosystem condition and (re)-introducing missing (usually large) species as a way to restore those ecological processes. Conceptualizations of rewilding and actual rewilding projects draw on a wide range of cultural and ecological ideas and practical knowledge, which are detailed in this article. Several organizations now represent rewilding interests to policymakers and the public and set up or facilitate rewilding initiatives in Europe and the Americas. Much of their philosophies, practice, data, and outcomes are not published. The Wildland Research Institute is an influential source of research on wilderness mapping, rewilding, restoration, and policy analysis in Europe. The European Centre for Nature Conservation (ECNC) supports and facilitates the conservation of large herbivore populations and their habitats at large scales in Eurasia through its Large Herbivore Network. Rewilding Europe implements rewilding projects throughout Europe, bringing together financing for large herbivore reintroductions and luxury wilderness tourism. Their European Rewilding Network brings together rewilding-related services and knowledge exchange. Similarly, the True Nature Foundation is a European foundation that works to restore habitats, reintroduce primarily large herbivores, and create sustainable tourism in nature areas. Wild Europe seeks to promote and lobby for the protection of large, “wild” natural areas. Similarly, the European Wilderness Society is an advocacy organization that identifies and promotes the stewardship and protection of large wilderness areas. The Rewilding Foundation is an international organization promoting and working toward the conservation of large areas of habitat and corridors for large carnivores. The Wildlands Network is an American organization that similarly seeks to conserve and connect large habitat areas and reintroduce apex predators. The Rewilding Institute in the United States also promotes protecting large habitats and creating corridors for large carnivores. There are also numerous site-based rewilding projects, which largely preceded the consolidation of rewilding as a concept. Many of these, through their creative rethinking of ecological and paleo-ecological orthodoxy, have influenced the development of rewilding practice and theory.

scholarly journals Risks and opportunities of trophic rewilding for arthropod communities

2018 ◽  
Vol 373 (1761) ◽  
pp. 20170441 ◽  
Author(s):  
Roel van Klink ◽  
Michiel F. WallisDeVries
Keyword(s):  
Biodiversity Conservation ◽  
A Priori ◽  
Grey Literature ◽  
Control Treatment ◽  
Arthropod Communities ◽  
Large Herbivore ◽  
Large Herbivores ◽  
Natural Processes ◽  
Published Evidence ◽  
Eukaryotic Organisms

Trophic rewilding is a restoration strategy focusing on the restoration of trophic interactions to promote self-regulating, biodiverse ecosystems. It has been proposed as an alternative to traditional conservation management in abandoned or defaunated areas. Arthropods constitute the most species-rich group of eukaryotic organisms, but are rarely considered in rewilding. Here, we first present an overview of direct and indirect pathways by which large herbivores and predators affect arthropod communities. We then review the published evidence of the impacts of rewilding with large herbivores on arthropods, including grey literature. We find that systematic monitoring is rare and that a comparison with a relevant control treatment is usually lacking. Nevertheless, the available data suggest that when the important process of top-down control of large-herbivore populations is missing, arthropod diversity tends to decrease. To ensure that rewilding is supportive of biodiversity conservation, we propose that if natural processes can only partially be restored, substitutes for missing processes are applied. We also propose that boundaries of acceptable outcomes of rewilding actions should be defined a priori , particularly concerning biodiversity conservation, and that action is taken when these boundaries are transgressed. To evaluate the success of rewilding for biodiversity, monitoring of arthropod communities should be a key instrument. This article is part of the theme issue ‘Trophic rewilding: consequences for ecosystems under global change’.

scholarly journals Historical changes in land use influence current habitat preferences of large herbivores

2019 ◽  
Vol 34 (10) ◽  
pp. 2251-2259 ◽  
Author(s):  
Kajetan Perzanowski ◽  
Maciej Januszczak ◽  
Rafał Łopucki
Keyword(s):  
Land Use ◽  
Spatial Distribution ◽  
Habitat Preferences ◽  
Field Research ◽  
Study Data ◽  
European Bison ◽  
Large Herbivore ◽  
Large Herbivores ◽  
Historical Changes ◽  
Effective Factor

Abstract Context Predicting habitat use patterns is a key issue in the management of large herbivore populations. Particularly, indicators providing a model of the spatial distribution of a population in a simple way, without the necessity of laborious field research, are still being sought. Analysis of historical landscape changes can be one of such predictive tools. Objectives We tested the hypothesis that historical changes in land use can be used as an effective factor enabling prediction of spatial distribution. As a case study, data on habitat preferences of European bison Bison bonasus (wisents) were used. Methods Spatial distribution of 17302 records of the presence of wisents, collected over the period of 10 years, was compared using contemporary and historical habitat maps for the Bieszczady Mts. (Poland). The area of approx. 87 thousand ha was selected, where the density of human population decreased over four times, and the percentage of forests increased from over 30% to almost 80% due to land abandonment. Results Wisents were recorded significantly more frequently in parts of the forest that in the past were used for agriculture. We found that identification of parts of the forest overgrowing former cultivated fields makes it possible to predict the spatial distribution of wisent herds with very high probability. Conclusions Information on historical changes in land use can be used as a simple and effective factor enabling prediction of habitat selection by wisents. Such an approach can potentially be useful for similar assessments of other large wild herbivores.

Sign in / Sign up

Export Citation Format

Share Document